The result of using externally hexed implants is that it becomes difficult, if not impossible, to remove the impression jig after making an impression, especially when the implant is disposed at an angle to the direction of release of the impression. This is particularly so when more than one implant is involved. This is because utilising the previous technology is inappropriate because the external hex (driving flats) tends to impede the removal of the resultant impression because relative side-ways movement of the impression relative to the implant is precluded by virtue of the interengagement of the externally hexed implant and a sleeve in contact with it.